The present invention pertains generally to the field of chemical agent vapor generator systems which are used for specialized purposes. Such purposes include calibrating and testing chemical agent detectors, challenging protective respirators such as gas masks with a controlled concentration of chemical agent to determine respirator protection factors, and similar applications involving toxic chemicals. These systems typically utilize chemical warfare agents such as Tabun (GA), Sarin (GB), Soman (GD), Cyclosarin (GF), Lewisite (L), Sulfur mustard gas (HD, H, HT, HL, HQ), Nitrogen mustard gas (HN1, HN2, HN3), and V-Agents (VE, VG, VM, VR, VX). In addition to such chemical warfare agents, these vapor generator systems may be used with toxic industrial chemicals and toxic industrial materials. The present invention comprises a safety release device for preventing the possible over-pressurization of such systems, which could cause component failure and the uncontrolled release of toxic chemicals. For the purposes herein, the phrase “surety system” will be used to refer to any system designed to operate with chemical warfare agents, toxic industrial chemicals, toxic industrial materials, or any combination thereof.
A chemical agent vapor generator system that would benefit from the present invention is described in U.S. Pat. No. 5,728,927, which is incorporated herein by reference. The system of the '927 patent provides a means for creating a conditioned chemical agent airstream through the blending of a chemical agent airstream with a controlled relative humidity airstream. The '927 system, however, relies on a traditional flask bubbler with a rubber stopper to generate the controlled relative humidity airstream. Over-pressurization within this system, as well as other similar vapor generator systems, can occur because of a downstream blockage of gas flow, an excess inlet flow rate, or other causes. Such over-pressurization can result in a component failure and the uncontrolled release of toxic chemicals. For example, the rubber stopper of the traditional flask bubbler can be forced out of the flask if the pressure is too great thus resulting in an uncontrolled release of gas or the uncontrolled dispersion of broken glass. While it is possible to include pressure relief valves as components within chemical agent vapor generator systems either upstream or downstream of the flask bubbler, or both upstream and downstream, there are limitations to this approach. Even with such precautions of including one or more pressure relief valves within the system it is still possible that the local pressure at the flask bubbler could exceed the safe working pressure of the flask bubbler if, for example, a flow blockage occurred between the flask bubbler and the relief valve. In addition, for such surety systems, minimizing the number of components is desirable because of the exposure of these components to toxic chemicals and the corresponding need for decontamination and special handling.
The present invention overcomes these problems by providing a vapor generator with combined bubbler and pressure relief means and a limited number of parts which are easy to clean and decontaminate.